High pressure mass analyzer

Abstract

In one aspect, a mass spectrometer is disclosed, which comprises a Fourier Transform (FT) mass analyzer having an input port for receiving ions and an exit port through which the ions exit the FT mass analyzer, a detector disposed downstream of said FT analyzer for detecting ions exiting the FT analyzer, and a multi-segment ion guide having a plurality of segments, said multi-segment ion guide being disposed upstream of said FT mass analyzer and having an input port for receiving ions and an output port through which ions exit the FT mass analyzer. The segments of the ion guide are configured to be independently activated via application of a DC offset voltage thereto so as to adjust a length through which ions passing through the ion guide experience collisional cooling.

What is claimed is: 
     
       1. A mass spectrometer, comprising:
 a Fourier Transform (FT) mass analyzer having an input port for receiving ions and an exit port through which the ions exit the FT mass analyzer, 
 a detector disposed downstream of said FT analyzer for detecting ions exiting the FT analyzer, and 
 a multi-segment radiofrequency (RF) ion guide having a plurality of segments, said multi-segment ion guide being disposed upstream of said FT mass analyzer and having an input port for receiving ions and an output port through which ions exit the FT mass analyzer, 
 wherein said segments of the multi-segment ion guide are configured to be independently activated via application of a DC offset voltage thereto so as to adjust a length through which ions passing through the ion guide experience collisional cooling. 
 
     
     
       2. The mass spectrometer of  claim 1 , wherein a number of segments of said multi-segment RF ion guide is in a range of about 2 to about 200. 
     
     
       3. The mass spectrometer of  claim 1 , wherein said multi-segment RF ion guide is configured to permit adjusting said length in a range of about 10 mm to about 1000 mm. 
     
     
       4. The mass spectrometer of  claim 1 , wherein each segment of said multi-segment RF ion guide comprises a plurality of rods arranged in a multi-pole configuration. 
     
     
       5. The mass spectrometer of  claim 4 , wherein said RF multi-pole configuration comprises any of quadrupole, hexapole and octupole configuration. 
     
     
       6. The mass spectrometer of  claim 5 , further comprising at least one DC voltage source for applying said DC offset voltage to said segmented RF ion guide. 
     
     
       7. The mass spectrometer of  claim 6 , wherein said DC voltage source applies said DC offset voltage to at least one of said segments of the multi-segment RF ion guide via application of the DC offset voltage to at least one of said plurality of rods of said segment. 
     
     
       8. The mass spectrometer of  claim 1 , wherein said FT analyzer comprises a plurality of rods arranged in a multi-pole configuration. 
     
     
       9. The mass spectrometer of  claim 1 , wherein said multi-segment RF ion guide is maintained at a pressure in a range of about 1 e −4  torr to about 5 e −3  torr. 
     
     
       10. The mass spectrometer of  claim 1 , wherein said FT mass analyzer is maintained at a pressure in a range of about 1 e −6  torr to about 5 e −3  torr. 
     
     
       11. The mass spectrometer of  claim 8 , further comprising an RF voltage source for applying an RF voltage to one or more segments of said multi-segment RF ion guide for radial confinement of said ions as they pass through said segmented ion guide. 
     
     
       12. The mass spectrometer of  claim 8 , further comprising an AC voltage source for applying an excitation voltage to at least one rod of said FT mass analyzer so as to excite radial secular frequencies of a plurality of ions. 
     
     
       13. The mass spectrometer of  claim 12 , wherein said excited ions interact with fringing fields in vicinity of a distal end of the FT analyzer such that radial oscillations thereof are converted into axial oscillations. 
     
     
       14. The mass spectrometer of  claim 13 , wherein said FT mass analyzer comprises an auxiliary electrode and wherein said AC voltage source applies said excitation voltage to said auxiliary electrode. 
     
     
       15. The mass spectrometer of  claim 1 , further comprising a multipole mass analyzer disposed upstream of the multi-segment RF ion guide. 
     
     
       16. The mass spectrometer of  claim 15 , further comprising an ion guide disposed upstream of said multi-pole mass analyzer for receiving ions from an upstream source and focusing said ions. 
     
     
       17. The mass spectrometer of  claim 15 , wherein said multipole mass analyzer comprises a plurality of rods arranged according to any of a quadrupole, hexapole or octupole configuration.